Emission testing was conducted in May 1996 on a commercial tug as part of a general Coast Guard R&D study to evaluate protocols for shipboard emissions testing. The objectives of this test were to determine emissions data for a commercial tug, evaluate fuel savings techniques, and evaluate portable testing protocols for emissions testing. Portable emission analyzers were used that employ electrochemical sensors. The NOx values determined were below both the International Maritime Organization's (IMO) and Environmental Protection Agency's (EPA's) maximum allowable levels for a 1225 RPM rated engine. A commercial engine speed pilot was installed with a fuel management system to record fuel consumption, engine horsepower, and provide a capability of balancing the engines for optimum running efficiency. An indication of fuel savings was apparent when the engine speed pilot was engaged.